Methods and apparatus for controlling photoresist line width roughness with enhanced electron spin control

ABSTRACT

The present invention provides methods and an apparatus for controlling and modifying line width roughness (LWR) of a photoresist layer with enhanced electron spinning control. In one embodiment, an apparatus for controlling a line width roughness of a photoresist layer disposed on a substrate includes a processing chamber having a chamber body having a top wall, side wall and a bottom wall defining an interior processing region, a support pedestal disposed in the interior processing region of the processing chamber, and a plasma generator source disposed in the processing chamber operable to provide predominantly an electron beam source to the interior processing region.

CROSS REFERENCE TO RELATED APPLICATION

This application claims benefit of U.S. Provisional Patent ApplicationNo. 61/497,370, filed Jun. 15, 2011, which is incorporated by referencein its entirety.

BACKGROUND

1. Field of the Invention

The present invention generally relates to methods and apparatus forcontrolling photoresist line width roughness and, more specifically, tomethods and apparatus for controlling photoresist line width roughnesswith enhanced electron spin control in semiconductor processingtechnologies.

2. Description of the Related Art

Integrated circuits have evolved into complex devices that can includemillions of components (e.g., transistors, capacitors and resistors) ona single chip. The evolution of chip designs continually requires fastercircuitry and greater circuit density. The demands for greater circuitdensity necessitate a reduction in the dimensions of the integratedcircuit components.

As the dimensions of the integrated circuit components are reduced (e.g.to sub-micron dimensions), more elements are required to be put in agiven area of a semiconductor integrated circuit. Accordingly,lithography processes have become more and more challenging to transfereven smaller features onto a substrate precisely and accurately withoutdamage. In order to transfer precise and accurate features onto asubstrate, a desired high resolution lithography process requires havinga suitable light source that may provide radiation at a desiredwavelength range for exposure. Furthermore, the lithography processrequires transferring features onto a photoresist layer with minimumphotoresist line width roughness (LWR). After all, a defect-freephotomask is required to transfer desired features onto the photoresistlayer. Recently, an extreme ultraviolet (EUV) radiation source has beenutilized to provide short exposure wavelengths so as to provide afurther reduced minimum printable size on a substrate. However, at suchsmall dimensions, the roughness of the edges of a photoresist layer hasbecome harder and harder to control.

FIG. 1 depicts an exemplary top isometric sectional view of a substrate100 having a patterned photoresist layer 104 disposed on a targetmaterial 102 to be etched. Openings 106 are defined between thepatterned photoresist layer 104 readily to expose the underlying targetmaterial 102 for etching to transfer features onto the target material102. However, inaccurate control or low resolution of the lithographyexposure process may cause in poor critical dimension control in thephotoresist layer 104, thereby resulting in unacceptable LWR 108. LargeLWR 108 of the photoresist layer 104 may result in inaccurate featuretransfer to the target material 102, thus, eventually leading to devicefailure and yield loss.

Therefore, there is a need for a method and an apparatus to control andminimize LWR so as to obtain a patterned photoresist layer with desiredcritical dimensions.

SUMMARY

The present invention provides methods and an apparatus for controllingand modifying LWR of a photoresist layer with enhanced electron spincontrol. In one embodiment, an apparatus for controlling a line widthroughness of a photoresist layer disposed on a substrate includes aprocessing chamber having a chamber body having a top wall, side walland a bottom wall defining an interior processing region, a supportpedestal disposed in the interior processing region of the processingchamber, and a plasma generator source disposed in the processingchamber operable to provide predominantly an electron beam source to theinterior processing region.

In another embodiment, a method for controlling line width roughness ofa photoresist includes providing a substrate having a patternedphotoresist layer in a processing chamber, supplying a gas mixture intothe processing chamber, generating a plasma in the gas mixture havingelectrons moving in a circular mode from the gas mixture, generating amagnetic field to enhance the electrons in the plasma moving in thecircular mode to a substrate surface, and trimming an edge profile ofthe patterned photoresist layer disposed on the substrate surface withthe enhanced electrons.

In another embodiment, a method for controlling line width roughness ofa photoresist layer disposed on a substrate includes providing asubstrate having a patterned photoresist layer disposed thereon into aprocessing chamber, supplying a gas mixture into the processing chamber,generating a plasma in the gas mixture, extracting electrons out of theplasma, generating a magnetic field to enhance the electrons moving in acircular mode to a substrate surface, and trimming an edge profile ofthe patterned photoresist layer disposed on the substrate surface withthe enhanced plasma.

In yet another embodiment, a method for controlling line width roughnessof a photoresist layer disposed on a substrate includes supplying a gasmixture into a processing chamber having a substrate disposed therein,wherein the substrate has a patterned photoresist layer disposedthereon, generating a plasma in the processing chamber from the gasmixture supplied in the processing chamber, applying a voltage to ashield plate disposed in the processing chamber to filter ions from theplasma and leaving mild reactive species, directing the mild reactivespecies through a control plate, applying a DC or AC power to a group ofone or more electromagnetic coils disposed around an outer circumferenceof the processing chamber to generate a magnetic field, enhancingmovement of the mild reactive species in circular mode by passing themild reactive species through the magnetic field, and trimming an edgeprofile of the patterned photoresist layer using the mild reactivespecies.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention are attained and can be understood in detail, a moreparticular description of the invention, briefly summarized above, maybe had by reference to the embodiments thereof which are illustrated inthe appended drawings.

FIG. 1 depicts a top isometric sectional view of an exemplary structureof a patterned photoresist layer disposed on a substrate conventionallyin the art;

FIG. 2A depicts a schematic cross-sectional view of an inductivelycoupled plasma (ICP) reactor with enhanced electron spin control usedaccording to one embodiment of the invention;

FIG. 2B depicts an electron trajectory diagram according to oneembodiment of the invention;

FIG. 3 depicts an electron trajectory diagram passing through a beamcontrol plate disposed in the ICP reactor depicted in FIG. 2;

FIG. 4 depicts a flow diagram of one embodiment of performing aphotoresist line width roughness control process according to oneembodiment of the present invention;

FIG. 5 depicts a top view of electron trajectories traveled adjacent toa photoresist layer according to one embodiment of the presentinvention; and

FIG. 6 depicts a profile of a line width roughness of a photoresistlayer disposed on a substrate according to one embodiment of theinvention.

FIG. 7 depicts one embodiment of a control plate and/or a shield plate;

FIG. 8 depicts another embodiment of a control plate and/or a shieldplate; and

FIG. 9 depicts yet another embodiment of a control plate and/or a shieldplate.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

It is to be noted, however, that the appended drawings illustrate onlyexemplary embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

DETAILED DESCRIPTION

Embodiments of the present invention include methods and apparatus forcontrolling LWR of a photoresist layer disposed on a substrate. The LWRof a photoresist layer may be controlled by performing an ICP processwith enhanced electron spin control on a photoresist layer after anexposure/development process. The ICP process is performed to provide achemical and electron grinding process on a nanometer scale withenhanced electron spin control to smooth the edge of the photoresistlayer pattern with sufficient electron spin momentum, thereby providinga smooth pattern edge of the photoresist layer with minimum pattern edgeroughness for subsequent etching processes. The ICP process withenhanced electron spin control may also be used to etch a targetmaterial disposed underneath the photoresist layer on the substratesubsequent to the photoresist line edge roughness minimization process.

FIG. 2A depicts a schematic, cross-sectional diagram of one embodimentof an ICP reactor 200 suitable for performing plasma processing withenhanced electron spin control according to the present invention. Onesuch etch reactor that may be adapted for performing the invention maybe available from Applied Materials, Inc., of Santa Clara, Calif. It iscontemplated that other suitable plasma processing chambers may also beemployed herein, including those from other manufacturers.

The plasma reactor 200 includes a processing chamber 248 having achamber body 210. The processing chamber 248 is a high vacuum vesselhaving a vacuum pump 228 coupled thereto. The chamber body 210 of theprocessing chamber 248 includes a top wall 222, a sidewall 224 and abottom wall 226 defining an interior processing region 212 therein. Thetemperature of the sidewall 224 is controlled using liquid-containingconduits (not shown) that are located in and/or around the sidewall 224.The bottom wall 226 is connected to an electrical ground 230.

The processing chamber 248 includes a support pedestal 214. The supportpedestal 214 extends through the bottom wall 226 of the processingchamber 248 into the interior processing region 212. The supportpedestal 214 may receive a substrate 250 to be disposed thereon forprocessing.

A plasma generator source 202 is attached to top of the chamber body 210configured to supply electrons to the interior processing region 212. Aplurality of coils 208 may be disposed around the plasma generatorsource 202 to insist creating inductively coupled plasma from the plasmagenerator source 202.

Processing gases may be introduced to the interior processing region 212from a gas source 206 coupled to the processing chamber 248. Theprocessing gases from the gas source 206 are supplied to the interiorprocessing region 212 through the plasma generator source 202. Currentis applied to the coil 208 from a power source which creates an electricfield that dissociates the processing gases. The processing gasesdissociated by the coils 208 form an electron beam 249 to be deliveredto the interior processing region 212 for processing.

A group of one or more coil segments or electromagnetic coils 221 (shownas 221A and 221B) are disposed around an outer circumference of a lowerportion 211 of the chamber body 210 adjacent to the interior processingregion 212. Power to the coil segment(s) or magnets 221 is controlled bya DC power source or a low-frequency AC power source (not shown). Theelectromagnetic coils 221 generate a magnetic field in a directionperpendicular to the substrate surface where the electron beam 249 isintroduced into the processing chamber 248. As the electrons from theelectron beam 249 may not have sufficient momentum to reach down to theinterior processing region 212 further down to an upper surface 253 ofthe substrate 250, the group of the coil segments or electromagneticcoils 221 may be disposed at the lower portion 211 of the chamber body210 (e.g., close to the interior processing region 212) to enhancespinning and/or whirling of the electrons down to the upper surface 253of the substrate 250. The interaction between the electric field andmagnetic field generated from the group of the coil segments orelectromagnetic coils 221 causes the electron beam 249 having enhancedelectron spinning and/or whirling momentum to reach down to the surfaceof the substrate 250. It is noted that other magnetic field sourcescapable of generating sufficient magnetic field strength to promote anelectron beam (e-beam) source may also be used.

In one embodiment, a shield plate 262 is disposed in the processingchamber 248 above the support pedestal 214. The shield plate 262 is asubstantially flat plate comprising a plurality of apertures 270. Theshield plate 262 may be made of a variety of materials compatible withprocessing needs, comprising one or more apertures 270 that definedesired open areas in the shield plate 262. In one embodiment, theshield plate 262 may be fabricated from a material selected from a groupconsisting of copper or copper coated ceramics. The open areas of theshield plate 262 (i.e., the size and density of the apertures 270)assist in controlling the amount of ions/electrons which mainly consistof an electron beam and small amounts of ions formed from the plasmagenerator source 202 to the interior processing region 212 above theupper surface 253 of the substrate 250. Accordingly, the shield plate262 acts as an ion/electron filter (or electron controller) thatcontrols the electron density and/or ion density in the volume passingthrough the shield plate 262 to the upper surface 253 of the substrate250.

During processing, a voltage from a power source 260 may be applied tothe shield plate 262. The voltage potential applied on the shield plate262 may attract ions from the plasma, thereby efficiently filtering theions from the plasma, while allowing only neutral species, such asradicals and electrons, to pass through the apertures 270 of the shieldplate 262. Thus, by reducing/filtering the amount of ions through theshield plate 262, grinding or smoothing of the structures formed on thesubstrate by neutral species, radicals, or electrons, i.e., mildreactive species, can be processed in a more controlled manner.Therefore, the mild reactive species may reduce the likelihood ofundesired erosion sputter, or overly aggressive ion bombardment that maycause to the substrate surface to roughen, thereby resulting in precisesmoothing performance and critical dimension uniformity. The voltageapplied to the shield plate 262 may be supplied at a range sufficient toattract or retain ions from the plasma, thereby repelling the neutralspecies, radicals, or electrons from the ions generated in the plasma.Thus, the mild reactive species are extracted from the plasma by theshield plate 262. In one embodiment, the voltage is applied to theshield plate 262 from the power source 260 between about 50 volts DC andabout 200 volts DC. In another embodiment, the mild reactive species areextracted from the plasma by the shield plate 262 are predominantlyelectrons.

A control plate 264 is disposed below the shield plate 262 and above thesupport pedestal 214. The control plate 264 has a plurality of apertures268 that allow the neutral species, radicals, or electrons filteredthrough the shield plate 262 to pass therethrough into the interiorprocessing region 212. The control plate 264 is positioned in aspaced-apart relationship with the shield plate 262 at a predetermineddistance 266. In another embodiment, the control plate 264 is attachedto the shield plate 262 with minimum space in between. In oneembodiment, the distance 266 between the shield plate 262 and thecontrol plate 264 is less than about 20 mm.

A voltage from a power source 251 may be applied to the control plate264, so as to create a voltage potential (e.g., an electrical potential)that interacts with the magnetic field generated from the group of thecoil segments or electromagnetic coils 221 (shown as 221A and 221B). Theelectrical potential generated by the control plate 264 along with themagnetic field generated by the group of the coil segments orelectromagnetic coils 221 assist and enhance maintaining sufficientmomentum and energy to keep the neutral species, radicals, or electronsspinning down to the upper surface 253 of the substrate 250.Furthermore, the neutral species, radicals, or electrons passing throughthe apertures 268 of the control plate 264 may be directed in apredetermined path, thereby confining the trajectory of the neutralspecies, radicals, or electrons in a predetermined path to reach to adesired area on the upper surface 253 of the substrate 250. When passingthrough the control plate 264, the magnified field may cause the neutralspecies, radicals, or electrons passing through to keep moving in acircular mode and spinning toward to the upper surface 253 of thesubstrate 250. The spin electrons have to grid the structures withsufficient momentum to bottoms of the structures formed on the uppersurface 253 of the substrate 250.

In one embodiment, the control plate 264 may have different materials ordifferent characteristics. The control plate 264 may comprise more thanone zone or segments having at least one characteristic that isdifferent from each other. For example, the control plate 264 may have anumber of zones with different configurations including variousgeometries (e.g., sizes, shapes and open areas) and the zones may bemade of the same or different materials, or be adapted to have differentpotential bias or different powers. By providing combinations of zoneconfigurations, materials, powers, and/or potential bias, the spatialdistribution of the neutral species, radicals, and electrons in theplasma may be modified in a localized manner, allowing customization ofprocess characteristics, such as smoothing uniformity or locallyenhanced or reduced smoothing rates (e.g., to tailor to differentpattern densities in different parts of a substrate) and so on. Such amulti-zone control plate 264 may be used to actively control the neutralspecies, radicals, and electrons distribution, and thus, allow forenhanced process control. More embodiment of the control plate 264 willbe further discussed below with reference to FIGS. 7-9.

During substrate processing, gas pressure within the interior of theprocessing chamber 248 may be controlled in a predetermined range. Inone embodiment, the gas pressure within the interior processing region212 of the processing chamber 248 is maintained at about 0.1 to 999mTorr. The substrate 250 may be maintained at a temperature of betweenabout 10 to about 500 degrees Celsius.

Furthermore, the processing chamber 248 may include a translationmechanism 272 configured to translate the support pedestal 214 and thecontrol plate 264 relative to one another. In one embodiment, thetranslation mechanism 272 is coupled to the support pedestal 214 to movethe support pedestal 214 laterally relative to the control plate 264. Inanother embodiment, the translation mechanism 272 is coupled to theplasma generator source 202 and/or the control plate 264 and/or theshield plate 262 to move the plasma generator source 202 and/or thecontrol plate 264 and/or the shield plate 262 laterally relative to thesupport pedestal 214. In yet another embodiment, the translationmechanism 272 moves one or more of plasma generator source 202, thecontrol plate 264 and shield plate 262 laterally relative to the supportpedestal 214. Any suitable translation mechanism may be used, such as aconveyor system, rack and pinion system, an x/y actuator, a robot,electronic motors, pneumatic actuators, hydraulic actuators, or othersuitable mechanism.

The translation mechanism 272 may be coupled to a controller 240 tocontrol the scan speed at which the support pedestal 214 and plasmagenerator source 202 and/or the control plate 264 and/or the shieldplate 262 move relative to one another. In addition, translation of thesupport pedestal 214 and the plasma generator source 202 and/or thecontrol plate 264 and/or the shield plate 262 relative to one anothermay be configured to be along a path perpendicular to the predeterminedtrajectory 274 of the neutral species, radicals, or electrons the uppersurface 253 of the substrate 250. In one embodiment, the translationmechanism 272 moves at a constant speed, of approximately 2 millimetersper seconds (mm/s). In another embodiment, the translation of thesupport pedestal 214 and the plasma generator source 202 and/or thecontrol plate 264 and/or the shield plate 262 relative to one anothermay be moved along other paths as desired.

The controller 240, including a central processing unit (CPU) 244, amemory 242, and support circuits 246, is coupled to the variouscomponents of the reactor 200 to facilitate control of the processes ofthe present invention. The memory 242 can be any computer-readablemedium, such as random access memory (RAM), read only memory (ROM),floppy disk, hard disk, or any other form of digital storage, local orremote to the reactor 200 or CPU 244. The support circuits 246 arecoupled to the CPU 244 for supporting the CPU 244 in a conventionalmanner. These circuits include cache, power supplies, clock circuits,input/output circuitry and subsystems, and the like. A software routineor a series of program instructions stored in the memory 242, whenexecuted by the CPU 244, causes the reactor 200 to perform a plasmaprocess of the present invention.

FIG. 2A only shows one exemplary configuration of a plasma reactor thatcan be used to practice the invention. For example, other types ofreactors may utilize different types of plasma power and magnetic powercoupled into the plasma chamber using different coupling mechanisms. Insome applications, different types of plasma may be generated in adifferent chamber from the one in which the substrate is located, e.g.,remote plasma source, and the plasma subsequently guided into thechamber using techniques known in the art.

FIG. 3 depicts an electron trajectory diagram passing through thecontrol plate 264 depicted in FIG. 2 according to one embodiment of theinvention. As the filtered neutral species, radicals, and electrons(e.g., electron beam source) passing through the shield plate 262 areaccelerated toward the upper surface 253 of the substrate 250, thefiltered neutral species, radicals, and electrons (e.g., electron beamsource) subsequently passing through the control plate 264 may beconfined to pass through the apertures 268 formed in the control plate264. As the group of electromagnetic coils 221 are disposed around thecontrol plate 264, the neutral species, radicals, and electrons (e.g.,electron beam source) passing therethrough may keep orbiting around andtravelling down in the predetermined trajectory 274 confined by theapertures 268 of the control plate 264 and reach desired regions on theupper surface 253 of the substrate 250. By utilization of the controlplate 264, the trajectory 274 of the neutral species, radicals, andelectrons (e.g., electron beam source) may be efficiently controlled ina manner with enhanced electron spinning momentum so as to enableelectrons to travel deep down to the bottom of the structures formed onthe substrate while continuing to spin around the horizontal plane sothat the electrons grind and smooth the roughness from the edge of thestructures formed on the substrate 250.

FIG. 4 illustrates a flow diagram of one embodiment of performing aphotoresist LWR control process 400 according to one embodiment of theinvention. The process 400 may be stored in memory 242 as instructionsthat executed by the controller 240 to cause the process 400 to beperformed in an ICP processing chamber, such as the ICP reactor 200depicted in FIG. 2A or other suitable reactors.

The process 400 begins at a block 402 by transferring a substrate, suchas the substrate 250 depicted in FIG. 2A, into the processing chamber248 for processing. The substrate 250 may have a target material 512 tobe etched disposed thereon, as shown in FIG. 6, disposed under aphotoresist layer 514. In one embodiment, the target material 512 to beetched using the photoresist LWR control process 400 may be a dielectriclayer, a metal layer, a ceramic material, or other suitable material. Inone embodiment, the target material 512 to be etched may be a dielectricmaterial formed as a gate structure or a contact structure or aninter-layer dielectric structure (ILD) utilized in semiconductormanufacturing. Suitable examples of the dielectric material includeSiO₂, SiON, SiN, SiC, SiOC, SiOCN, amorphous-carbon (a-C), or the like.In another embodiment, the target material 512 to be etched may be ametal material formed as an inter-metal dielectric structure (IMD) orother suitable structures. Suitable examples of metal layers include Cu,Al, W, Ni, Cr, or the like.

At block 404, a photoresist LWR control process 400 may be performed onthe substrate 250 to grind, modify and trim edges 516 of the photoresistlayer 514, as shown in FIG. 5. The photoresist LWR control process 400is performed providing a source of electrons. In one embodiment, theelectrons are providing by generating an ICP in the processing chamber248. The ICP is generated by the plasma generator source 202 disposed inthe processing chamber 248. As discussed above, the plasma as generatedmay include different types of reactive species, such as electrons,charges, ions, neutral species, and so on either with positive ornegative charges. The excited plasma is used to extract electrons whichare moved and accelerated in a circular motion toward the upper surface253 of the substrate 250.

At block 406, as the plasma is advanced toward the substrate surface,the plasma then passes through the shield plate 262 disposed in theprocessing chamber 248. A voltage is applied to the shield plate 262 tocreate a voltage potential, so as to attract ions from the plasma,thereby efficiently filtering ions from the plasma, while allowing onlyneutral species, such as radicals and electrons (e.g., electron beamsource), to pass through the apertures 270 of the shield plate 262 tothe substrate surface. In one embodiment, the voltage is applied to theshield plate 262 from power source 260 between about 50 volts DC andabout 200 volts DC.

At block 408, after passing through the shield plate 262, the filteredplasma (e.g., electron beam source) then travels through the controlplate 264. The control plate 264 may confine the filtered plasma passingtherethrough to a predetermined path so as to increase collimation ofthe filtered plasma (e.g., electron beam source) such that the mildreactive species fall on certain regions of the upper surface 253 of thesubstrate 250. The filtered plasma (e.g., electron beam source) isaccelerated to maintain a substantially helical movement circulated bythe magnetic field generated from the group of the electromagnetic coils221 such that the mild reactive species have sufficient momentum tomaintain a spinning motion down to the upper surface 253 of thesubstrate 250. A power supplied to the control plate 264 may generate anelectric field to interact with the magnetic field generated from thegroup of the electromagnetic coils 221 to enhance/maintain the helicalmotion of the mild reactive species such that sufficient momentum andenergy is provided to keep the mild reactive species spinning down tothe upper surface 253 of the substrate 250. The spin electrons may,thus, grind the structures with sufficient momentum all the way tobottoms of the structures formed on the upper surface 253 of thesubstrate 250.

At block 410, the LWR of the photoresist layer 514 may be adjusted,grinded, modified, controlled during the plasma-induced process. Asdepicted in FIG. 5, the circular movement 504 of the electrons maysmoothly grind, collide, and polish away the uneven edges 516 of thephotoresist layer 514. The process may be continuously performed until adesired degree of roughness, e.g., straightness, (as shown by imaginaryline 510) of photoresist layer 514 is achieved. By a good control of theelectron momentum, the uneven surfaces and protrusions from edges 516 ofthe photoresist layer 514 may be gradually flattened out, therebyefficiently controlling the photoresist LWR within a desired minimumrange. The electron momentum or neutral species concentration may becontrolled by the power generated from the interaction between themagnetic field and the electric field and the gases supplied thereto. Inone embodiment, by adjusting the power supplied to generate the plasmapower and the magnetic field, different electron momentum or mobilitymay be obtained.

In one embodiment, the distribution of the electrons and/or neutralspecies (e.g., electron beam source) may be controlled by using adifferent control plate 264 with different materials or differentcharacteristics. More embodiments of the control plate 264 withdifferent materials or different characteristics will be furtherdiscussed below with reference to FIGS. 7-9.

During processing, at block 410, several process parameters may becontrolled to maintain the LWR of the photoresist layer 514 at a desiredrange. In one embodiment, the plasma power may be supplied to theprocessing chamber between about 50 watts and about 2000 watts. Themagnetic field generated in the first group of coils or magneticsegments 208 in the processing chamber may be controlled between about500 Gauss (G) and about 1000 G. A DC and/or AC power between about 100watts and about 2000 watts may be used to generate a magnetic field inthe processing chamber. The magnetic field generated in the group ofelectromagnetic coils 221 in the processing chamber may be controlledbetween about 100 G and about 200 G. A DC and/or AC power may be appliedto the control plate 264 between about 100 watts and about 2000 watts togenerate a magnetic field in the processing chamber. The voltage betweenabout 50 volts DC and about 200 volts DC is applied to the shield plate262 to filter the plasma as generated from the plasma generator 202. Thepressure of the processing chamber may be controlled at between about0.5 milliTorr and about 500 milliTorr. A processing gas may be suppliedinto the processing chamber to assist modifying, trimming, andcontrolling the edge roughness of the photoresist layer 514. As thematerials selected for the photoresist layer 514 are often organicmaterials, an oxygen containing gas may be selected as the processinggas to be supplied into the processing chamber to assist gridding andmodifying the roughness and profile of the photoresist layer 514.Suitable examples of the oxygen containing gas include O₂, N₂O, NO₂, 0₃, H₂O, CO, CO₂, and the like. Other types of processing gas may also besupplied into the processing chamber, simultaneously or individually, toassist in modifying the roughness of the photoresist layer 514. Suitableexamples of the processing gas include N₂, NH₃, Cl₂ or inert gas, suchas Ar or He. The processing gas may be supplied into the processingchamber at a flow rate between about 10 sccm to about 500 sccm, forexample, about between about 100 sccm to about 200 sccm. The process maybe performed between about 30 seconds and about 200 seconds. In oneparticular embodiment, the O₂ gas is supplied as the processing gas intothe processing chamber to react with the photoresist layer 514 so as totrim and modify the LWR of the photoresist layer 514 disposed on thesubstrate 250.

The photoresist LWR control process 400 may be continuously performeduntil a desired minimum roughness of the photoresist layer 514 isachieved. In one embodiment, line width roughness 513 of the photoresistlayer 514 may be controlled in a range less than about 3.0 nm, such asbetween about 1.0 nm and about 1.5 nm. The photoresist LWR controlprocess 400 may be terminated after reaching an endpoint signalindicating that a desired roughness of the photoresist layer 514 isachieved. Alternatively, the photoresist LWR control process 400 may beterminated by a preset time mode. In one embodiment, the photoresist LWRcontrol process 400 may be performed for between about 100 seconds andbetween about 500 seconds.

FIG. 6 depicts an exemplary embodiment of a cross sectional view of thephotoresist layer 514 already having the photoresist LWR control process400 performed thereon. After the photoresist LWR control process 400 isperformed, a smooth edge surface is obtained. The roughness of thephotoresist layer 514 is smoothed out and trimmed in a manner tominimize the edge roughness and smooth the edge morphology of thephotoresist layer 514. The smooth edge surface formed in the photoresistlayer 514 defines a sharp and well defined opening 604 in the patternedphotoresist layer 514 to expose the underlying target material 512 foretching, thereby etching a precise and straight opening width 606 to beformed as a mask layer. In one embodiment, the width 606 of the openings604 may be controlled between about 15 nm and about 35 nm.

In one embodiment, the underlying target material 512 may be etched byan etching process performed in the same chamber used to perform the LWRcontrol process, such as the processing chamber 248 depicted in FIG. 2.In another embodiment, the underlying target material 512 may be etchedby an etching process performed in any other different suitable etchingchamber integrated in a cluster system where the LWR processing chambermay be incorporated thereto. In yet another embodiment, the underlyingtarget material 512 may be etched by an etching process performed in anyother different suitable etching chambers, including a stand-alonechamber separated from the LWR process chamber or separated from acluster system where the LWR processing chamber may be incorporatedthereto.

In one embodiment, the gas mixture utilized to perform the LWR processis configured to be different from the gas mixture utilized to etch theunderlying target material 512. In one embodiment, the gas mixtureutilized to perform the LWR process includes an oxygen containing gas,such as O₂, and the gas mixture utilized to etch the underlying targetmaterial 512 includes a halogen containing gas, such as fluorine carbongas, chlorine containing gas, bromide containing gas, fluorinecontaining gas, and the like.

FIG. 7 depicts one embodiment of a plate 700 having different zones invarious arrangements. In the embodiment depicted in FIG. 7, the plate700 has different zones, 702, 704, 706 arranged in concentric rings. Theplate 700 may be used as one or both of a control plate or shield platein the embodiment of FIG. 2A. The concentric ring configuration, forexample, may be useful in compensating for plasma non-uniformities (in aradial direction) that may arise from non-uniform gas flow patterns inthe chamber.

FIG. 8 depicts another embodiment of a plate 800 having different zonesin various arrangements. The plate 800 may be used as one or both of acontrol plate or shield plate in the embodiment of FIG. 2A. In theembodiment depicted in FIG. 8, the plate 800 is configured to have zonesor segments based on the specific mask patterns in order to achievedifferent smoothing rate resulted on the substrate surface. The plate800 is divided into two zones 802, 804, whose spatial configurationscorrespond to or correlate with respective regions on a mask havingdifferent pattern densities. For example, if zone 802 corresponds to aregion on the mask requiring a relatively higher smoothing rate than therest of the mask, then zone 802 may be provided with a larger diameterof apertures 806. Alternatively, zones 802, 804 may be made of materialswith different dielectric contacts and/or different potential biases, soas to provide different electron (and/or neutral species) spinning orrotating rates.

FIG. 9 depicts yet another embodiment of a plate 900 having differentzones in various arrangements. The plate 900 may be used as one or bothof a control plate or shield plate in the embodiment of FIG. 2A. In theembodiment depicted in FIG. 9, the plate 900 is configured to have aplurality of zones or segments 902, 904, 906, 908. At least two zonesare made of different materials compatible with process chemistries. Atleast two zones may be independently biased to maintain a potentialdifference between the biased zones. The use of materials havingdifferent dielectric constants or different potential biases allowsusers to tune the plasma characteristics or different rotating speedsand momentums. Additionally, the sizes of apertures 910, 912, 914, 916located in different zones 902, 904, 906, 908 of the plate 900 may bearranged in any combinations or configurations.

Thus, the present invention provides methods and an apparatus forcontrolling and modifying LWR of a photoresist layer with enhancedelectron spinning momentum. The method and apparatus can advantageouslycontrol, modify and trim the profile, line width roughness and dimensionof the photoresist layer disposed on a substrate after a light exposureprocess, thereby providing accurate critical dimension control of anopening in the photoresist layer so the subsequent etching process mayaccurately transfer critical dimensions to the underlying layer beingetched through the opening.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. An apparatus for controlling a line width roughness of a photoresistlayer disposed on a substrate, comprising: a processing chamber having achamber body having a top wall, side wall and a bottom wall defining aninterior processing region; a support pedestal disposed in the interiorprocessing region of the processing chamber; and a plasma generatorsource disposed in the processing chamber operable to providepredominantly an electron beam source to the interior processing region.2. The apparatus of claim 1, further comprising: a shield plate disposedin the processing chamber operable to filter ions from the plasma andpass electrons.
 3. The apparatus of claim 2, further comprising: acontrol plate disposed in the processing region between the shield plateand the support pedestal.
 4. The apparatus of claim 3, furthercomprising: a power source coupled to the control plate.
 5. Theapparatus of claim 3, wherein the control plate comprises a plurality ofzones formed therein with at least two zones comprising differentmaterials or different potential biases.
 6. The apparatus of claim 2,further comprising: a power source coupled to the shield plate.
 7. Theapparatus of claim 2, wherein the shield plate comprises a plurality ofzones formed therein with at least two zones comprising differentmaterials or different potential biases.
 8. The apparatus of claim 3,wherein the control plate is attached to the shield plate.
 9. Theapparatus of claim 3, wherein the control plate has a plurality ofapertures formed therein.
 10. The apparatus of claim 1, wherein theshield plate has a plurality of apertures formed therein.
 11. Theapparatus of claim 1 further comprising: a magnet or a group of one ormore electromagnetic coils disposed around an outer circumference of thechamber body adjacent to the interior processing region of the chamberbody.
 12. A method for controlling line width roughness of a photoresistlayer disposed on a substrate comprising: providing a substrate having apatterned photoresist layer disposed thereon into a processing chamber;supplying a gas mixture into the processing chamber; generating a plasmain the gas mixture having electrons moving in a circular mode from thegas mixture; generating a magnetic field to enhance the electrons in theplasma moving in the circular mode to a substrate surface; and trimmingan edge profile of the patterned photoresist layer disposed on thesubstrate surface with the enhanced electrons.
 13. The method of claim12, wherein generating the plasma further comprises: filtering ions fromthe plasma.
 14. The method of claim 13, further comprising: directingthe filtered electrons through the magnetic field.
 15. The method ofclaim 12, wherein generating the magnetic field further comprises:applying a DC or AC power to one or more electromagnetic coils disposedaround the outer circumference of the processing chamber.
 16. The methodof claim 12, wherein the gas mixture comprises an oxygen containing gas.17. A method for controlling line width roughness of a photoresist layerdisposed on a substrate comprising: supplying a gas mixture into aprocessing chamber having a substrate disposed therein, wherein thesubstrate has a patterned photoresist layer disposed thereon; generatinga plasma in the processing chamber from the gas mixture supplied in theprocessing chamber; applying a voltage to a shield plate disposed in theprocessing chamber to filter ions from the plasma and leave mildreactive species; directing the mild reactive species through a controlplate; applying a DC or AC power to a group of one or moreelectromagnetic coils disposed around an outer circumference of theprocessing chamber to generate a magnetic field; enhancing movement ofthe mild reactive species in circular mode by passing through thefiltered plasma in the magnetic field; and trimming an edge profile ofthe patterned photoresist layer using the mild reactive species.
 18. Themethod of claim 17, wherein directing the filter plasma furthercomprises: applying a power to the control plate.
 19. The method ofclaim 17, wherein supplying the gas mixture further comprises: supplyingan oxygen containing gas into the processing chamber.
 20. The method ofclaim 17, wherein the mild reactive species include neutral radicals andelectrons.